Starship Asterisk*

NGC 1566
http://www.astrobin.com/230020/0/
Copyright: Ray Johnson

NGC 6894
http://www.capella-observatory.com/Imag ... GC6894.htm
Copyright: Volker Wendel, Stefan Binnewies and Josef Pöpsel

Elephant Trunk Nebula
http://astrophotography.aa6g.org/Astrop ... f8300.html
Copyright: Chuck Vaughn

starsurfer wrote:NGC 289
http://www.astro-austral.cl/imagenes/ga ... 9/info.htm
Copyright: José Joaquín Pérez
max.jpg

Thanks for posting so many great galaxy images here, starsurfer and bystander! I love them all, but I think that José Joaquín Pérez' portrait of NGC 289 is of particular interest. Just look at those bright, colorful, starbursting and nebula-popping inner arms, and compare them with the incredibly wide-ranging, long and faint outer arms. At least one of the outer arms winds more than one full turn around the galaxy, and then there are numerous broken arm fragments and ring structures. This galaxy is like an iceberg, with only one tenth of it "sticking up out of the darkness". Incredible!

Note that the outer arms are bluish-gray in color, which clearly suggests that most of their light comes from young and intermediate-aged stars. I think these arms are fairly young structures. Perhaps we can spot the interloper that has been responsible for stirring up the gas reserves in the halo surrounding NGC 289 and making it "go spiral". At 9 o'clock is a small but extended faint oval structure, which is all gray and all non-blue in color. This must be a spheroidal dwarf galaxy which is paying NGC 289 a visit and making waves, or rather spirals, as it goes!

Ann

IC 3481
http://bf-astro.com/ic3481/ic3481.htm
Copyright: Bob Franke

Twilight Rays at La Silla
ESO Picture of the Week | 2016 Nov 21

[img3="Credit: R. Wesson/ESO"]https://cdn.eso.org/images/screen/potw1647a.jpg[/img3][hr][/hr]

As the Sun sets on another day at La Silla, the observatory’s staff members are able to start doing what they do best — observing and exploring the night sky! La Silla was ESO’s first observatory, and remains one of the most productive observatories in the world.

This photograph captures the last few rays of sunlight, producing a striking blend of orange, red and yellow close to the horizon. More prominent, however, are the bright star trails streaking and curving through the sky. Each of these trails is formed by the motion of an individual star, captured over a long exposure time. Vehicles also form light trails from their rear headlights as they move, lighting up the network of roads throughout the region.

This picture was taken by ESO Photo Ambassador Roger Wesson. To show both twilight and the growing star trails in the same image, Wesson combined 763 different 20-second exposures, beginning approximately 40 minutes after sunset and continuing through the night.

Hubble Spies NGC 3274
ESA Hubble Picture of the Week | 2016 Nov 21

[img3="Credit: ESA/Hubble & NASA, D. Calzetti"]https://cdn.spacetelescope.org/archives ... w1647a.jpg[/img3][hr][/hr]

This image of the spiral galaxy NGC 3274 comes courtesy of the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3). Hubble’s WFC3 vision spreads from the ultraviolet light through to the near infrared , allowing astronomers to study a wide range of targets, from nearby star formation through to galaxies in the most remote regions of the cosmos.

This particular image combines observations gathered in five different filters, bringing together ultraviolet, visible, and infrared light to show off NGC 3274 in all its glory. As with all of the data Hubble sends back to Earth, it takes advantage of the telescope’s location in space above our planet’s distorting atmosphere. WFC3 returns clear, crisp, and detailed images time after time.

NGC 3274 is a relatively faint galaxy located over 20 million light-years away in the constellation of Leo (The Lion). The galaxy was discovered by Wilhelm Herschel in 1783. The galaxy PGC 213714 is also visible on the upper right of the frame, located much further away from Earth.

How absolutely fascinating!!!

Just last week, bystander posted the picture at left of dwarf irregular galaxy NGC 4789A, and I was quite unimpressed with the looks of it. The galaxy looks just "faint all over", with some scattered little sprinklings of blue across the face of it. There are no large clusters there, no bright nebulas, nothing. Yet the U-B and B-V colors of NGC 4789A are extraordinarily blue, -0.270 and 0.300, respectively.

Now bystander has just posted a picture of another small galaxy, NGC 3274, which compared with NGC 4789A has a much higher surface brightness. We can tell that from the fact that the brightness of NGC 3274 peaks in the middle, whereas NGC 4789A is just faint everywhere.

And doesn't NGC 3274 look blue, compared with NGC 4789A? Look at all those bright clusters and obvious nebulas. It's much bluer than NGC 4789A, isn't it?

Well, looks are deceiving. The U-B and B-V color indexes of NGC 3274 are "only" -0.140 and 0.390, clearly less blue than the colors of NGC 4789A! How is that possible?

Well, we must bear in mind that the two images are not directly comparable, since different filters have been used for the two pictures. But an important part of the answer is that NGC 3274, with its much higher surface brightness, clearly has a much more substantial old yellow population than NGC 4789A. I think that is the major reason why NGC 4789A is bluer than NGC 3274, namely, that the old yellow population of the former galaxy is so weak.

There is one more reason why NGC 3274 is redder than NGC 4789A, and that is dust. To me, NGC 4789A looks all but dust-free, whereas NGC 3274 contains several visible clouds of dust. NGC 3274 is slightly brighter in the far infrared than in the B magnitude, which implies healthy amounts of dust and a good source of raw material for new star formation. But this dust has probably also reddened the light that reaches us from NGC 3274.

To me this is just so fascinating!!!

Ann

Andromeda Galaxy (M31)
http://www.astrosurf.com/ilizaso/orriak ... Q_U16m.htm
Copyright: Iñaki Lizaso

vdB143
http://www.astrobin.com/268800/?nc=user
Copyright: Tero Turunen

Rainbow at dusk Copyright: Marcello AMARI

Rainbow at dusk II
Copyright: Marcello AMARI

LDN 673
http://www.astropilar.com.ar/nebulosas/LDN673_1.html
Copyright: Ezequiel Bellocchio

NGC 1579
https://www.flickr.com/photos/andyinsea/23413080789/
Copyright: Andy Ermolli

NGC 300
http://www.atacama-photographic-observa ... .php?id=52
Copyright: Thierry Demange, Richard Galli and Thomas Petit

Markarian's Chain
http://www.pbase.com/tango33/image/160396891
Copyright: Kfir Simon

The Swimming Moon
ESO Picture of the Week | 2016 Nov 28

[img3="Credit: Petr Horálek/ESO"]https://cdn.eso.org/images/screen/potw1648a.jpg[/img3][hr][/hr]

The famously dry Atacama Desert may seem like an odd place for the Moon to take a dip — but in this intriguing image, taken by ESO Photo Ambassador Petr Horálek, it appears to do just that!

Initially high, the crescent Moon slowly descends through the clear Chilean sky, before hitting the thickest parts of the atmosphere right above the horizon.

It was here that a “rare theatre” began, said Horálek. The thin sliver of the Moon was optically distorted into a “weird, snaky shape” as its light passed through layers of different air densities, caused by different pressures, temperatures and humidities. The Moon lost its smooth curves and instead appeared as a rippling and squiggly zig-zag — “as if it were swimming”. The effect of the closely spaced layers in the atmosphere caused different parts of the Moon’s image to be refracted differently as it disappeared below the horizon.

All these pictures were taken at ESO’s La Silla Observatory in Chile, facing the Pacific Ocean.

Spotlight on IC 3583
ESA Hubble Picture of the Week | 2016 Nov 28

[img3="Credit: ESA/Hubble, NASA"]https://cdn.spacetelescope.org/archives ... w1648a.jpg[/img3][hr][/hr]

This delicate blue group of stars — actually an irregular galaxy named IC 3583 — sits some 30 million light-years away in the constellation of Virgo (The Virgin).

It may seem to have no discernable structure, but IC 3583 has been found to have a bar of stars running through its centre. These structures are common throughout the Universe, and are found within the majority of spiral, many irregular, and some lenticular galaxies. Two of our closest cosmic neighbours, the Large and Small Magellanic Clouds, are barred, indicating that they may have once been barred spiral galaxies that were disrupted or torn apart by the gravitational pull of the Milky Way.

Something similar might be happening with IC 3583. This small galaxy is thought to be gravitationally interacting with one of its neighbours, the spiral Messier 90. Together, the duo form a pairing known as Arp 76. It’s still unclear whether these flirtations are the cause of IC 3583’s irregular appearance — but whatever the cause, the galaxy makes for a strikingly delicate sight in this NASA/ESA Hubble Space Telescope image, glimmering in the blackness of space.

A nice but large (800 Kb) portrait of M90 and IC 3583 can be seen here.

Ann

Ann wrote:A nice but large (800 Kb) portrait of M90 and IC 3583 can be seen here.

Ann

There are hardly any amateur images of M90.

The Pleiades or Seven Sisters (Messier 45 or M45), is an open star cluster containing middle-aged, hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky. The celestial entity has several meanings in different cultures and traditions.
The cluster is dominated by hot blue and extremely luminous stars that have formed within the last 100 million years.source wikipedia.

http://themaurosky.wixsite.com/astropho ... leiadi-m45